Although the existence of functional sequelae in comitant strabismus, i.e., anomalous retinal correspondence, suppression, and amblyopia are well-known, relatively little is known about the real character of possible anomalous cooperation between the fixing and the deviated eye of a strabismic subject in his/her everyday seeing conditions. This project will deal with clinical experiments to identify the extension of area of binocular single vision in patients with small-angle esotropia and to find the appropriate test-stimuli interfering as little as possible with the casual seeing conditions of the patient. Results obtained with tests having different "dissociating" power will be compared. We hope to demonstrate that in some cases anomalous retinal correspondence is the only anti-diplopic mechanism used by patients, that a suppression mechanism conditions for the first time in exotropes. Finally, the phenomenon of the prismcompensation (or "eating up of prisms") will be extensively studied in exotropic patients, in order to compare their behavior with that of esotropic patients. This phenomenon, considered to be a sensory-motor sequel of strabismus, is believed to be fusional in nature.